Carl Icahn is always in the news. He’s usually being demonized for some allegedly ego-driven play to take over a company. I don’t care what his reasons are, as long as they’re aimed at making his shareholders some money.

That’s right, I said, “shareholders.” You can actually buy a piece of Vulture Carl, and had I known that was the case a few years back, I’d have bought some stock right away in Icahn Enterprises LP (NASDAQ:IEP). Plus, since Icahn owns 80% of the stock, you can be certain his interests are aligned with shareholders — although it also means he doesn’t have to listen to a thing they say.

IEP owns businesses in several sectors. Among its holdings: automobile raw material and parts supplier Federal-Mogul; six hotel and casinos under the Tropicana brand; 54% of American Railcar Industries; 71% of Viskase Companies, a food packaging company; PSC Metals, which processes and sells scrap metals; a real estate operation that handles rentals, development and resort activities; and WestPoint International, a company that consists of manufacturing, sourcing, marketing, distributing and selling home-fashion consumer products.

Many of these entities were purchased out of bankruptcy — Tropicana and WestPoint come to mind — allowing Icahn to negotiate true vulture capital deals that are very much to his and his shareholders’ benefit. That’s why I put IEP in the must-own category of mogul-run companies along with John Malone’s Liberty Media (NASDAQ:LMCA) and Liberty Interactive (NASDAQ:LINTA),Barry Diller’s IAC Interactive (NASDAQ:IACI), Warren Buffett’s Berkshire Hathaway (NYSE:BRK.A) and the other great conglomerate Leucadia National (NYSE:LUK).

These guys are so much better than a mutual fund manager because they’re often using their own money or have high ownership of the stock, and they use moderately priced unsecured debt, or equity, if need be.

Speaking of cash flow, that’s also how you evaluate each company’s success. Earnings from conglomerates can be seasonal and volatile. Icahn generated almost $2 billion of cash flow in fiscal 2011. You may be distressed to see only $85 million in cash flow in Q1, but the same period last year saw negative $447 million before ending big.

Icahn’s company, like Leucadia and Liberty, also provide a snapshot of the economy to give you direction on your other holdings. For example, the rail segment saw a 138% revenue increase because demand drove increased railcar shipments. That bodes well for other rail stocks and manufacturing in general, since railcars carry raw materials and finished products.

The automotive segment saw a 5% increase in revenue, so people are still fixing their cars and not putting off repairs. But gaming remains a challenge, as increased volume was offset by lower table hold percentages. That means the house had to lower its rake in order to attract more players. The result was flat performance.

The stock is gaining traction at $43 after hitting a post-financial-crisis low of $26 — landing there after a fall from $120. It’s a good time to get in. Plus, IEP pays a 2.3% dividend, of which 40% comes in cash and 60% in additional LP units. That’s another thing to watch. Set up as a limited partnership, Icahn Enterprises may have tax consequences because you’ll get a K-1 each year. Consult your accountant to learn more.